Pedalboard patchbay.

Usually it's convenient to have all the connections between pedals, amp and guitar groupped in one box. It does not only reduce the cable mess, but also makes the transportation easier. This box was designed to serve as such device, provide the signal buffering and multiple outputs for use in homerecording and multi amp applications.

Buffer/Splitter/Patchbay

Design goals:

  • high input impedance, more than 1.5MOhm,
  • two non isolated outputs,
  • two transformer isolated outputs with MUTE switches,
  • patchbay for connections between amps input and effect loop,
  • standard 9V DC power input.

SCHEMATIC

SCHEMATIC 2

(version with FX loop bypass footswitch)


Buffer/Splitter Buffer/Splitter Buffer/Splitter


Construction:

As you can see on the schematic, the circuit is quite simple. Four voltage followers for the signal patch, low impedance bias voltage source. On the main output, which feeds the pedals placed in front of the amp, i used a non polarised MKT 10uF/63V coupling cap. If you can't find one, you can always use 3...4 1uF MKT caps in parallel (enough for most applications) or just plain aluminium 10uF electrolytic cap.

Buffer/Splitter/Patchbay

 Use any quad JFET input low noise opamp for the signal buffers (like TL074 or OPA4227) and a single opamp for the virtual ground buffer. I've use the cheap Xicor TM018 10k:10k transformers. Driven from the low impedance source they do the job just fine.

One of the isolated outputs is used as balanced XLR output. I'm using it for recording a dry guitar track. Usefull trick to experiment with software amp simulators or reamping.